1. Field of the Invention
The present invention discloses a near-field scanning optical microscope. The microscope includes a lighting component, a probe and an ellipsoidal mirror. The lighting component emits a light. The probe is disposed on one side of a testing sample, and the light. is focused around a probe tip to draw the near-field light out. The ellipsoidal mirror has a first focal point and a second focal point, and the first focal point and the probe tip are disposed at the corresponding positions respectively, and the near-field light drawn out from the probe tip is scattered from the first focal point inside the ellipsoidal minor, and reflected and passed through the second focal point.
2. Description of the Related Art
With reference to FIG. 1 for a conventional measuring technique by using a near-field microscope for a near-field optical scanning, FIGS. 1(a), 1(b) and 1(c) show an aperture probe. Although a smaller aperture of the probe 4 can improve the resolution, yet a light 2 passing through an aperture has a weaker power, and a near-field light 14 drawn out from the probe 4 and received by a microscope 21 is very weak and difficult to be analyzed. FIG. 1(d) shows an apertureless probe, wherein after the light 2 is projected and the near-field light 14 drawn out from the probe 4 is scattered in different directions, and the microscope 21 is provided for collecting the scattered near-field light in a far-field distance, only a very small portion of the scattered near-field light 14 is received by the microscope 21, so that the received light is very weak. Even though the light is transmitted to a photomultiplier tube for an electro-optical signal transformation and signal amplification, it is relatively difficult to analyze the near-field optical signal from the high background noise.
With reference to FIG. 2 for a conventional microscope disclosed in J. Appl. Phys. 83 (3), pages 1171˜1176 by C. Durkan and I. V. Shvets in 1998, such microscope includes an optical fiber used as a probe 4, and a large-sized ellipsoidal mirror, wherein a piezoelectric ceramic tube P1 for driving the probe 4 and a piezoelectric ceramic tube P2 for driving a testing sample are included inside the ellipsoidal mirror 5, so that the overall size becomes too large. In addition, the optical fiber probe and the mirror must be coaxial with each other. The photomultiplier tube 12 is installed on a second focal point of the ellipsoidal mirror 5, and the first focal point and second focal point of the ellipsoidal mirror are disposed on both sides of the testing sample respectively. Therefore, part of a reflected light may be blocked by the piezoelectric ceramic tube P2 which drives the testing sample to lower the light receiving performance. In the meantime, the photomultiplier tube 12 is exposed directly to the outside, strong lights may damage the photomultiplier tube 12. In summation of the description above, the conventional microscope has existing drawbacks.
Obviously, the collected near-field light on the prior arts is very weak and difficult to be analyzed, and such technical problems require feasible solutions.